The present invention relates to a compound intraocular lens ("CIOL") for an eye.
During the last several decades, there has been a tremendous evolution of technology and an escalation of interest in refractive surgery for the eye. The most commonly performed refractive surgical procedure, cataract extraction with intraocular lens implantation, as well as more recently popularized corneal refractive surgical procedures, have a number of drawbacks and limitations. The lack of postoperative refractive accuracy vis-a-vis glasses and/or contact lenses is a common problem and is seen in all of these techniques. Those factors affecting the accuracy of IOL surgery include wound-induced or pre-existing astigmatism, anterior chamber depth and axial length measurement error.
A lack of refractive stability further complicates all known corneal procedures. Surgeons agree that the desired outcome of refractive surgery is to allow the patient to see without external correction with vision acuity approximately equivalent to the level the patient had with correction prior to surgery. Therefore, the refractive endpoint must hover between 20/20 and 20/25 uncorrected acuity in 95-99% of cases. Currently, the refractive accuracy of both IOL and corneal procedures falls significantly short of this goal. See Werblin, T. P. and Stafford, G. M., "The Casebeer System for Predictable Corneal Refractive Surgery. One Year Evaluation of 211 Consecutive Patients," Vol. 100 Ophthalmology at 1095-1102 (1993); Holladay, J. T. and Prager, T. C., et al., "Improving the Predictability of Intraocular Lens Power Calculations," Vol. 104 Arch Ophthalmology at 539-541 (1988); Werblin, M.D., Ph.D., T. P., "Should We Consider Clear Lens Extraction for Routine Refractive Surgery," Vol. 8 Journal of Refractive & Corneal Surgery at 480-81 (November/December 1992). These procedures have accuracy rates of +/-0.5 D to 1.0 D, resulting in 95-99% of patients postoperatively achieving 20/40 or better uncorrected vision. The goal of 20/25 or better uncorrected vision can be achieved only if the standard deviation of the refractive procedure is +/-0.25 D, at least twice the accuracy of any existing refractive surgical procedure.
Moreover, in traditional intraocular lens applications, the lens cannot be modified or enhanced once in place in the eye. The ability to fine-tune or enhance radial keratotomy to allow an increased level of accuracy as stated above depends upon another series of wound/healing events which are somewhat unpredictable (at least .+-.0.15 D).
Accordingly, there is a need for an intraocular lens which can be modified or enhanced once it is in place within the eye. There is also a need to be able to modify traditional intraocular lenses put in place following corneal transplant surgery.
Additionally, there is a need for an intraocular lens which can improve the current +/-0.75 D to 1.0 D refractive accuracy of IOL surgery to a desired +/-0.25 D.
Moreover, there is a further need for an IOL system which will allow the surgeon to postoperatively titrate the refraction after the patient's eye has healed from the initial surgery and the IOL position within the eye is stabilized.
Moreover, there is a need for an IOL system in which, in addition to being adjustable for spherical corrections, can accurately correct astigmatic errors, either congenital or induced, or which can include titratable cylindrical, multi-focal, bi-focal, tri-focal or predictable astigmatic corrections.